There are two issues with using CVS to store binary files. The first is that CVS by default converts line endings between the canonical form in which they are stored in the repository (linefeed only), and the form appropriate to the operating system in use on the client (for example, carriage return followed by line feed for Windows NT).
The second is that a binary file might happen to contain data which looks like a keyword (see Keyword substitution), so keyword expansion must be turned off.
The ‘-kb’ option available with some CVS commands insures that neither line ending conversion nor keyword expansion will be done.
Here is an example of how you can create a new file using the ‘-kb’ flag:
$ echo '$Id$' > kotest $ cvs add -kb -m"A test file" kotest $ cvs ci -m"First checkin; contains a keyword" kotest
If a file accidentally gets added without ‘-kb’,
one can use the
cvs admin command to recover.
$ echo '$Id$' > kotest $ cvs add -m"A test file" kotest $ cvs ci -m"First checkin; contains a keyword" kotest $ cvs admin -kb kotest $ cvs update -A kotest # For non-unix systems: # Copy in a good copy of the file from outside CVS $ cvs commit -m "make it binary" kotest
When you check in the file kotest the file is
not preserved as a binary file, because you did not
check it in as a binary file. The
admin -kb command sets the default keyword
substitution method for this file, but it does not
alter the working copy of the file that you have. If you need to
cope with line endings (that is, you are using
CVS on a non-unix system), then you need to
check in a new copy of the file, as shown by the
cvs commit command above.
On unix, the
cvs update -A command suffices.
(Note that you can use
cvs log to determine the default keyword
substitution method for a file and
cvs status to determine
the keyword substitution method for a working copy.)
However, in using
cvs admin -k to change the
keyword expansion, be aware that the keyword expansion
mode is not version controlled. This means that, for
example, that if you have a text file in old releases,
and a binary file with the same name in new releases,
CVS provides no way to check out the file in text
or binary mode depending on what version you are
checking out. There is no good workaround for this
You can also set a default for whether
cvs import treat a file as binary based on
its name; for example you could say that files who
names end in ‘.exe’ are binary. See Wrappers.
There is currently no way to have CVS detect
whether a file is binary based on its contents. The
main difficulty with designing such a feature is that
it is not clear how to distinguish between binary and
non-binary files, and the rules to apply would vary
considerably with the operating system.